package com.qidian.server.servlet;

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@SuppressWarnings("serial")
public class ValidateCodeServlet extends HttpServlet
{
	//定义随机生成的字符数组
	static char[] code = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
            'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y',
            'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
            'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y',
            'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };   
	//创建随机数生成器
	static Random rand = new Random();
	
	//定义获取指定范围内的随机颜色
	Color getRandColor(int fc, int bc) 
	{
        if (fc > 255) {
            fc = 255;
        }
        if (bc > 255) {
            bc = 255;
        }
        int n = Math.abs(fc - bc);
        int r = fc + rand.nextInt(n);
        int g = fc + rand.nextInt(n);
        int b = fc + rand.nextInt(n);
        return new Color(r, g, b);
    }

	Color getRandColor() 
	{
        return getRandColor(0, 255);
    }
	 @Override
	 protected void doGet(HttpServletRequest req, HttpServletResponse resp)
	   throws ServletException, IOException 
	 {
	  doPost(req, resp);
	 }
	 @Override
	 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
	   throws ServletException, IOException 
	 {
	   // 设置页面，禁止图像缓存
	  resp.setHeader("Pragma", "No-cache");
	  resp.setHeader("Cache-Control", "no-cache");
	  resp.setDateHeader("Expires", 0);
	
	     int width = 80; // 图像宽度
	     int height = 22; // 图像高度
	     int codeCount = 4; // 验证码长度
	
	     // 创建验证码图像image
	     BufferedImage image = new BufferedImage(width, height,
	             BufferedImage.TYPE_INT_RGB);
	     Graphics2D g = image.createGraphics();
	
	     // 设置验证码背景颜色
	     g.setColor(getRandColor(215, 255));
	     g.fillRect(0, 0, width, height);
	
	     // 设置验证码字体
	     g.setFont(new Font("Times New Roman", Font.PLAIN, height - 2));
	
	     // 设置验证码边框
	     //g.setColor(Color.BLACK);
	     //g.drawRect(0, 0, width - 1, height - 1);
	
	     // 随机生成60条干扰线
	     g.setColor(getRandColor(200, 220));
	     for (int i = 0; i < 30; i++) {
	         int x = rand.nextInt(width);
	         int y = rand.nextInt(height);
	         int xl = rand.nextInt(12);
	         int yl = rand.nextInt(12);
	         g.drawLine(x, y, x + xl, y + yl);
	     }

	     // 用一个randomCode来保存验证码
	     StringBuffer randomCode = new StringBuffer();
	
	     // 随机生成验证码
	     for (int i = 0; i < codeCount; i++) {
	         String randStr = String.valueOf(code[rand.nextInt(62)]);
	         g.setColor(getRandColor(0,120));
	         g.drawString(randStr, (rand.nextFloat() + 18) * i + 5, (rand
	         .nextFloat() + 3.5f) * 4);
	         randomCode.append(randStr); // 将随机产生的字符合成一个字符串
	     }
	     System.out.println(randomCode.toString());
	     // 将产生的验证码保存到session中
	     req.getSession().setAttribute(ServletConstants.s_attr_validate_code, randomCode.toString());

	     // 使图像生效
	     g.dispose();

	     // 将验证码图像输出到页面
	     ImageIO.write(image, "JPEG", resp.getOutputStream());
	     resp.getOutputStream().close();

	 }
}